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Discussion Starter #1
in the next few days i will attempt to modify the stock exhaust on the cbr250r. . i dont feel like spending $$$ on a new muffler, and have it be too loud and dirt bike sounding. i like the way the stock sounds with the intake door removed.. i wouldn't mind it a little deeper though so i will see what i can do.. ill post back with what i did in a few days.
 

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Drilling a few holes in the back around the outlet will add some sound and lower the back pressure a little. I saw one video where they managed to cut around the inner outlet pipe, which runs all the way to the front of the can, with a hole saw, and remove the whole pipe. That's pretty radical though as they may have had to drill and repair a tack weld at the front of the pipe to snake the whole thing out. You can also attack the inlet to crush up the cat and dump it out.
 

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i love exhaust mods, can't wait to see what you come up with.
 

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Discussion Starter #5
so, what i think im going to try to do is this. If you look at the stock exhaust the outlet hole has two diameters. An outer diameter circle thats larger and welded to the back of the muffler and then inside of it sites another circle of smaller diameter that seems to be the "db reduction insert" as it continues and pipes back into the muffler in an S bend.

Between those two diameters is a gap, if i can fit a hole saw or small drill bit in that gap and drill my way through to the inside of the muffler it should make a small by pass... or i can always try to fit a drill bit into the tube at an angle and try to drill some holes in that tube. i will try it today and let you guys know what happens. I'm trying to do it this way to keep the stock exhaust looking as clean as the stock exhaust can look, i think holes on the outside of the muffler looks kind of ugly and ghetto :p

ill report back soon.
 

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Between those two diameters is a gap, if i can fit a hole saw or small drill bit in that gap and drill my way through to the inside of the muffler it should make a small by pass
Good idea. Just take whatever drill bit will fit between the two outlet pieces and start drilling some holes. Start out with four at the quarter way around points of the circle to hear how loud it gets and keep going from there evenly spaced until you get the volume level you want. You may be able to go all the way around, just shy of touching the holes without weakening it too much before it gets too loud. The cops will never suspect it isn't stock if you lay out the holes evenly.
 

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Discussion Starter #8
Good idea. Just take whatever drill bit will fit between the two outlet pieces and start drilling some holes. Start out with four at the quarter way around points of the circle to hear how loud it gets and keep going from there evenly spaced until you get the volume level you want. You may be able to go all the way around, just shy of touching the holes without weakening it too much before it gets too loud. The cops will never suspect it isn't stock if you lay out the holes evenly.


hehe yea, sounds good.. ill give it a try.
 

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Discussion Starter #10
hey guys, so i attempted to do this, the original way that i tried didnt really work. that was trying to drill holes in between the two outlet pieces.. this didnt work because in between the two pieces the metal is at an angle and its too big of a pain in my a$$, the drill bit would just wiggle around.. :(.. so what i did is i took a rather small drill bit and just drilled holes even spaced out around the outside of the intlet, very closely as close as i could around the outlet hole, this bypassed the long snakey insert pipe, very tightly packed it didnt look bad. if you drill the holes nicely it doesnt look that ghetto to be honest. as fpr the sound i did notice and increase in the exhaust sound, the more you dril the more you will hear it, i also have the intake door removed so i hear alot of induction sound anyways. but over all it did increase the sound.. not a lot though.. so depending on what you want to do to the exhaust. if you dont care what it looks like then get the fattest drill bit you can get and just drill a hole in the back. that will make it loud. it was my birthday the other day and my brother got me a Leo vince exhaust lol... so i dont have to worryabout the stocker anymore.. ill post a vid of the leo if you guys want.... send bio hazard cycles an email about the leo's....my brother was able to get mine for $269 shipped
 
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